Nebulizer manifold

ABSTRACT

A manifold which introduces sterilant aerosol to a sterilization chamber for the disinfection of an article. The manifold defines the terminal portion of a fluid pathway from an aerosol generator to the sterilization chamber and comprises at least one chamber inlet port for introducing aerosol into the sterilizing chamber. The manifold is configured to provide directional aerosol flow tangential to the surface of the article, which is preferably of a known configuration and maintained in a predetermined position with respect to the manifold, such that it does not receive a direct flow of aerosol from the manifold. Preferably, the manifold is U-shaped, or bifurcate and defines a plane and with a chamber inlet ports are directed away from that plane. The chamber inlet ports are preferably paired so they create a circular motion of aerosol that moves around the article. Also sterilization apparatus including the manifold.

TECHNICAL FIELD

The invention relates to manifolds for controlling the flow of anaerosol in a defined manner. The invention is described primarily withreference to the introduction of a sterilant aerosol into a closedsterilisation chamber for the purpose of sterilising medical articlessuch as ultrasonic probes, although it will be appreciated that it isnot limited to such a use.

BACKGROUND ART

Any discussion of the prior art throughout the specification should inno way be considered as an admission that such prior art is widely knownor forms part of common general knowledge in the field.

Sterilizers are used in the medical, food and packaging industries tokill and thereby prevent the transmission of transmissible agents suchas spores, fungi, and bacteria. A typical sterilizer creates a set ofphysical conditions in a sterilisation chamber that effectively killsnearly all of these transmissible agents.

Contacting articles in need of sterilisation with sterilant aerosols isone known method of sterilisation. A conventional aerosol sterilisationapparatus has a sterilisation chamber with an aerosol inlet valve and anaerosol outlet valve, an aerosol generator (typically an ultrasonicnebulizer) in fluid communication with the chamber via the inlet valveand a fan upstream of, and in fluid communication with, the aerosolgenerator.

In use, an article requiring sterilisation is placed in the chamber,which is then sealed. The aerosol inlet valve is opened and the aerosoloutlet valve is closed. The fan is engaged, which creates a gas streamthrough or the past the aerosol generator into the chamber. A passivevent in the sterilisation chamber allows for pressure equalization asrequired, to permit gas flow in and out of the sterilisation chamber.The aerosol generator, which contains the desired sterilant, is thenactivated, putting a large number of small sterilant droplets into gasstream. The droplets are carried by the gas stream to create an aerosolwhich travels into the sterilisation chamber. The sterilantconcentration in the aerosol stream can be adjusted by changing eitherthe flow rate of the gas stream, the productivity of the aerosolgenerator, or the concentration of the liquid sterilant used.

The passive waste vent allows some flow to pass through it, allowing thesterilisation chamber to remain at approximately room pressure. Thispassive system may include a pathway for flow to the outside air pastcatalytic elements that react with the sterilant and break the sterilantdown into a safer chemistry suitable for disposal.

After a period of time, the fan and the aerosol generator aredeactivated and the air inlet valve is closed, hence completing thesterilant delivery phase. The exit valve is then opened and aerosol isactively removed, typically by way of a pump that pulls aerosol andvapour out of the sterilisation chamber at a high rate. The removalsystem may include a pathway for flow between the sterilisation chamberand outside air past catalytic elements that react with the sterilantand break the sterilant down into a safer chemistry suitable fordisposal. The passive vent allows a source of fresh air to be drawn intothe sterilisation chamber from the outside air.

It is generally desirable for the total sterilisation cycle time to beas short as possible. Short reprocessing durations increases the numberof times the sterilised article can be used in a given period, which inturn increases the number of patients per day that can be treated. Inthe case where the article to be sterilised is a high-cost medicaldevice, short cycle times can generate significant financial savings fora health care provider.

One of the limitations of using an aerosol-based sterilizer is that inorder to gain the required level of microbiological reduction in a shortsterilisation time a high concentration (ie a high mist density) ofaerosol sterilant is required. During sterilisation, a highconcentration of aerosol sterilant causes droplets to coalesce on thesurface of the article. This can be particularly prevalent at a locationon the article that is subject to a direct mist stream from the chamberinlet. This can also lead to multilayer B.E.T.-like absorption on thesurface of the sterilized article. Coalesced and absorbed droplets canbe difficult to remove from the article at the end of the sterilisationprocess. Large levels of residual sterilant left on the sterilisedarticle can be harmful to operators and patients and as such areundesirable in a fully automated sterilisation device.

While the residual sterilant may be removed by washing, this is anexpensive feature to add to an automated sterilisation device, andrequires sterile water and fresh water supplies that cannot always beeasily obtained. Alternatively, it is also undesirable to have staffhand-washing articles, as this requires the use of safety apparatuswhich can be expensive (such as fume hoods), can take up valuable timeand space and moreover increases the risk of harmful sterilant cominginto contact with an operator or patient.

A washing phase also requires a subsequent drying phase which addsconsiderably to apparatus turn-around times.

In conventional sterilization apparatus, the aerosol is usuallyintroduced into the sterilization chamber at a single point, via asingle chamber inlet port. As a result, the distribution of the aerosolparticles tends to fan out from that single point. More droplets contactthe article to be sterilised at a point close to the aerosol inlet port,and contact the article at higher velocity, leading to splattering onthe surface and the build up of condensate. Similarly, the areas of thearticle to be sterilised which are more remote from the aerosol inletmay receive a smaller dose of aerosol. In such cases, in order to ensuresterilization of the entire article, it becomes necessary to increasethe total sterilant dose to compensate for areas of the article that mayreceive a smaller dose.

Increasing sterilant dose may be achieved by increasing the length oftime to carry out the sterilisation or by increasing the amount ofsterilant delivered in a given time. Both methods can exacerbate thesplattering and condensation effect in areas close to the single chamberinlet port.

One method to reduce the level of condensation and splattering near theinlet port is to move the article to be sterilized further away from theinlet port, allowing it to better disperse before contacting thearticle. However, greater distances require larger sterilizationchambers, and this is undesirable for a number of reasons. Due to spacelimitations in many medical healthcare facilities, it is desirable forsterilisers to be as small as possible while still being capable ofhousing the article to be sterilized. Small sterilization chambers arealso advantageous because they are both faster to fill with sterilantand faster to remediate than larger chambers. However, a smallsterilization chamber increases the difficulty of introducing aerosolinto the chamber while having it contact the article in anevenly-distributed fashion.

Maintaining an even mist distribution inside a sterilization chamber isimportant to ensure that there is even sterilization of the article tobe sterilized. Once introduced into the sterilization chamber, aerosoldroplets tend to fall due to gravity which results in a greater mistconcentration at the bottom of the chamber than at the top of thechamber. In order to maintain an even distribution top to bottom, a highaerosol flow rate can be used to provide droplet lift. In this case thegas stream moves in an upward direction at a faster rate than dropletsfall. A downside of using such a method is that the gas streamvelocities used result in greater velocities for smaller droplets, andas there is typically a wide range of droplet sizes in an aerosol it isdifficult to optimise such a system. Additionally, the smaller andhigher-velocity droplets can collide with the article to coalesce on itssurface, thus making removal of residual sterilant difficult.

Using a dense mist is desirable, as it provides fast sterilization,which in turn can enable short sterilization cycles. However, inpractice, dense mists are susceptible to condensation. Prior artsterilizers often require noisy, large and expensive apparatus to removecondensation in a time-effective manner. Thus, in prior art sterilizers,in order to avoid condensation, the density of mist needs to be limited,meaning that short sterilization times cannot be realized.

Accordingly, there is a need to find improved methods of delivery of theaerosol to a sterilisation chamber, particularly a small chamber, sothat the aerosol is delivered to the article to be sterilised in an evenmanner and at a relatively low velocity to minimise the possibility ofcondensation.

SUMMARY OF THE INVENTION

According to a first aspect the invention provides a manifold forintroducing a sterilant aerosol to a sterilization chamber for thedisinfection of an article, the manifold defining the terminal portionof a fluid pathway from an aerosol generator to the sterilizationchamber; the manifold comprising at least one chamber inlet port forintroducing aerosol into the sterilizing chamber and being configured toprovide directional aerosol flow tangential to at least part of thesurface of the article.

Preferably the manifold is configured to provide directional aerosolflow tangential to at least part of the surface of an article maintainedin a predetermined position with respect to the manifold. It is alsopreferred that the manifold is configured to provide directional aerosolflow such that the article does not receive a direct flow of aerosolfrom the manifold. Preferably, the aerosol is directed not at thearticle.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising”, and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to”.

References to “sterilisation” and “disinfection” as used herein may beused interchangeably, and are also intended to include other levels ofmicrobial reduction, to including but not limited to sterilisation, highand low level disinfection.

An aerosol is a large number of discrete particles suspended in a gas.When the gas is directed into a stream or jet, the particles areentrained in the gas and move in a generally cohesive manner about themean path. However there will be a number of particles that followpathways deviating from the mean path. The more significantly any givenpath deviates from the mean path, the smaller the number of particlesthat follow such a path. Additionally, the further that a group ofaerosol particles travel from a common source, the more they disperse.Those skilled in the art will be well aware of such dispersive behaviourand will appreciate that in the present case, where a “direct”,“directed”, “tangential” or the like flow of an aerosol is disclosed,what is being referred to is the mean path taken by the droplets. Interms of the overall flow of aerosol under those circumstances, askilled person will interpret terms such as “direct”, “directed”,“tangential” and the like as meaning “substantially direct”,“substantially directed”, “substantially tangential” and so on.

Preferably the article is of a predetermined shape.

Preferably each chamber inlet port includes a nozzle or duct to directthe aerosol flow. The manifold preferably comprises at least two chamberinlet ports, and more preferably at least four chamber inlet ports.

The manifold can be a continuous manifold, or can comprise a number ofdiscrete sub-manifolds in fluid connection.

Preferably, the manifold defines a manifold plane and the chamber inletports are directed away from the manifold plane. In one embodiment, themanifold is a simple linear manifold that directs aerosol flowtangential to at least part of the surface of the article to besterilized. In further embodiments, the manifold is in more than oneplane and surrounds the article to be sterilised. The manifold can haveany suitable configuration, with regard to the size and shape of thesterilizing chamber and/or the size, shape and nature of the article tobe sterilized. In all cases though, the manifold has chamber inlet portsconfigured to direct aerosol flow tangential to at least part of thesurface of the article to be sterilized.

More preferably the manifold is configured to distribute aerosol fromaround the article to be sterilized and tangential to at least part ofthe surface thereoff for example, via a U-shaped, square, circular orsemi-circular, manifold.

Most preferably the manifold is U-shaped and defines a manifold planeand comprises diametrically opposed paired chamber inlet ports, suchthat a first port directs aerosol flow a first side of the manifoldplane and a second port directs aerosol flow to a second side of themanifold plane.

Preferably the manifold comprises diametrically opposed paired chamberinlet ports, such that a first port directs aerosol flow to a first sideof the manifold plane and a second port directs aerosol flow to a secondside of the manifold plane.

In one preferred configuration the manifold is U shaped and preferablyhas two, three or four vertically spaced apart chamber inlet ports,along each arm. Alternatively, the manifold is bifurcate and preferablyhas two, three or four vertically spaced apart chamber inlet ports,along each arm. However, any number of chamber inlet ports may bepresent, depending upon the size of the chamber and the degree ofaerosol particle size separation required.

The manifold can be formed from a single length of tubing.Alternatively, the manifold can be constructed such that is formed fromtwo mated portions that have been engaged with each other to form acomplete manifold. For example, the manifold may be formed from achannel which mates with a corresponding seal, such as when a channel inthe body of a sterilizing chamber mates with a corresponding seal on thedoor of the sterilizing chamber, and where both come into engagementwhen the door of the sterilizing chamber is shut.

The manifold is preferably in the form of an elongate tub, and is morepreferably of square cross section.

Preferably the manifold includes diametrically opposed paired chamberinlet ports which direct flow at a difference of angle of between 100and 260 degrees. Preferably the diametrically opposed paired chamberinlet ports create a circular motion of aerosol in the chamber thatmoves around the article.

Preferably the minimum distance between the article to be sterilized andthe manifold is less than 10 cm, more preferably less than 7 cm and evenmore preferably less than 5 cm.

Preferably the manifold inlet is located at the top of the manifold. Inone particularly preferred configuration the manifold inlet isbifurcated and splits aerosol flow into the top of the two arms of the Ushaped manifold.

According to a second aspect the invention provides sterilizationapparatus including a manifold according to the preceding aspect, asterilization chamber and detent means to maintain an article to besterilized at a predetermined position in the chamber, whereby theaerosol flow is tangential to at least part of the surface of thearticle. Preferably, the manifold does not direct the aerosol at thearticle to be sterilized.

Preferably the sterilization chamber defines a chamber volume andaerosol is admitted to the chamber at a rate of between one and threetimes the chamber volume per minute.

The sterilization apparatus preferably further includes a passive vent.More preferably, there is at least one aerosol exit point positionedabove the central vertical position of the chamber

The sterilization chamber is preferably adapted to hold an ultrasoundprobe.

The article is preferably an ultrasound probe, in which case thesterilization apparatus also preferably comprises a collar to sealinglyengage a portion of the article in the chamber and to restrain thepredetermined article from contact with the chamber walls. The chamberis elongate with a collar at the top to hold the probe in such a waythat the functional region of the probe is suspended substantially inthe middle of the chamber, and so that the functional region of theprobe is not in contact with the chamber walls. The manifold is locatedin a plane along the long axis of the ultrasound probe.

Preferably the chamber wall is heated. The manifold and chamber incombination are preferably configured to provide a vortexing aerosolflow. Preferably the article to be sterilized is at a point central tothe vortexing aerosol flow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sterilization apparatus including a manifold of thepresent invention.

FIG. 2 shows a sterilization apparatus including a manifold of thepresent invention, in which is placed an ultrasonic probe forsterilization.

FIG. 3 is a closer view of FIG. 2, with the sterilization apparatus doorremoved for clarity.

FIG. 4 is a close up view of the chamber inlet located on the manifold.

FIG. 5 is a cross sectional view of the gas flow from the manifold.

FIG. 6 is a cross sectional view of the gas flow from the manifold in achamber of substantially circular cross section.

FIG. 7 is a cross sectional view of the gas flow from a single sidedmanifold.

FIG. 8 is a cross sectional view of the gas flow from a single sidedmanifold in a chamber of substantially circular cross section.

FIG. 9 is a cross sectional view of the gas flow from an offset manifoldin a chamber of substantially circular cross section.

FIG. 10 is a cross sectional view of the gas flow from a single sidedmanifold in a chamber of substantially circular cross section, showingvortex separation of aerosol droplets on the basis of momentum.

DESCRIPTION

The present invention provides a means for creating and maintaining adense and even mist distribution in a sterilization chamber that ismarginally larger than the article (or articles) to be sterilized whilegreatly reducing condensation on the surface of the article.

These ends are met by directing aerosol tangential to the article to besterilized. The tangential flow reduces the likelihood of condensationwhen high aerosol velocities are present by using droplet deflection. Ithas been observed that droplets are less likely to adhere to a surfaceif they contact it at a shallow angle compared to contacting an articlein a perpendicular approach.

The manifold configuration of the present invention also provides alonger travel path for aerosol droplets, allowing aerosol to more fullydisperse before coming into contact with the article, hence improvingaerosol distribution in the sterilization chamber. The longer travelpath provided allows aerosol to reduce in velocity before coming intocontact with the article, hence reducing the likelihood of condensation.

The offset nature of the chamber inlet ports also allows them to bepositioned very close to the article without the threat of condensationforming on the surface of the article, hence facilitating a smallersterilization chamber.

By using multiple sterilant inlet ports, it is possible to more evenlycontrol the distribution of aerosol in the sterilization chamber.

By controlling the flow rate of aerosol into the sterilization chamber,the aerosol can be maintained at approximately equal concentrations atacross the vertical dimension of the chamber. An optimal flow rate isbetween one and three times the chamber volume per minute. Using higherflow rates may cause condensation on the surface of the article, andlower flow rates do not provide sufficient gas speed to allow dropletsto overcome gravitational effects.

Preferably, the aerosol inlet ports are directed away from each othersuch that the direction of flow from each port pair varies by between100 and 260 degrees. This provides an aerosol motion within the chamberthat is directed around the article to be sterilized that is largelyparallel or tangential to the surfaces on the device to be sterilized.The inlet ports need not be paired, ie on the same vertical plane, butcan be offset vertically. The nozzles can also be placed so that theyalternate in respect of which side of the article they are directedtowards.

The tangential flow can also be achieved by having the manifold ormanifolds offset from the central axis of the chamber.

Additionally, this tangential motion provides a means for separatinglarger droplets from smaller droplets. Larger droplets have higherlinear momentum and are more likely to collide with the heated chamberwall, rather than be carried around inwards with the gas flow toward thearticle to be sterilised. This reduces the possibility of large dropletscolliding with and condensing on the article. Providing a largely smoothchamber shape can help facilitate the vortex action (i.e. by roundingthe corners of the chamber to prevent the disruption of the vortex).Thus, vortex droplet separation can be achieved.

It is possible to heating the chamber walls to between 40 and 80 degreesCelsius in order to rapidly evaporate off any droplets that may havecondensed on the chamber walls due to the separation process, hencereducing the likelihood of a person coming into contact with condensedsterilant at any stage.

It is believed to be particularly advantageous to have the combinationof vortex droplet separation and heated chamber walls. The largerdroplets contact the chamber walls and evaporate, hence removingresidual droplets from the chamber wall, reducing the chance that theoperator could come into contact with harmful sterilant.

The invention will now be described with reference to the drawings.

FIG. 1 shows a steriliser 1 which has a sterilising chamber 2 whichincorporates the nebuliser manifold 3. The chamber comprises a rearportion 4, which is housed in the body of the sterilizer 5. The chamberalso has a front portion 6, in a mateable arrangement with the body.Closing the door 7 brings the front and rear portions of the chambertogether.

Closing the door causes the chamber front to mate with the chamber rearto seal the sterilization chamber.

Turning to FIG. 2, the sterilising chamber 2 is adapted to receive anelongate probe, for example, an ultrasound probe 10, that is insertedinto the open chamber, and held in a sealingly engaged manner by meansof a collar 11, such that the head of the probe 12 is not in contactwith any surface. When the chamber door 7 is closed and ultrasonic probe10 is in place, a sealed chamber results which has the probe 10suspended inside. The work surfaces of the probe are thus not in contactwith any surface.

Whilst collar 11 is shown as detent means for positioning the article toreceive a tangential flow, any suitable means such as brackets, mountingpins, clips etc may be used to maintain the article (such as anultrasound probe) in a position where it will receive only a tangentialaerosol flow, not a direct aerosol flow from the manifold. That is, themanifold directs the aerosol to the void space around the article, andnot at the article itself. Preferably the article is suspended in thechamber, which is as small as possible with regards to the article to besterilized—for example it is preferred if the distance between probe 10and chamber wall 2 or manifold 8 is less than a few centimetres.

FIG. 3 shows the sterilizer with the door 7 removed. The sealedsterilising chamber 2 is heated prior to use, along with the manifold 8.A fan not shown, in fluid connection with the manifold inlet ports 13and 14 (see FIG. 1), is then started. The air flows into the manifoldvia inlet ports 13 and 14, and into the manifold. The air flow exits themanifold by the chamber inlet ports 15, 16, 17, 18, 19, 20, 21 and 22,and enters the sterilization chamber. The manifold 8 is a continuoustubular tube, of square cross section as shown, although it can be ofany cross section, with a number of ports for introducing sterilisingagent to the chamber. The manifold is substantially U shaped, with theupper portion of the parallel arms 23 and 24 being stepped apart furtherthan the lower portion of the parallel arms 25 and 26.

Once the desired flow conditions are achieved, the ultrasonic nebulizer(not shown), which is in-line between the fan and the sterilizationchamber 2, is activated. A sterilant liquid, most typically hydrogenperoxide, is supplied to the nebuliser and is nebulised. The aerosolexits the nebuliser and joins the air flow. The aerosol is then movedvia the same path as the air flow, preferably a short path, to themanifold inlet ports 13 and 14 at the top of the manifold. Because theaerosol is under positive pressure, caused by the fan, and because thechamber has a passive exit vents 27 and 28 to allow the air pressure tobe equalised, the nebulant flows through the manifold 8, out of thechamber inlet ports 15, 16, 17, 18, 19, 20, 21 and 22 and into thesterilization chamber 2.

A typical nebulant mist as produced in the nebulizer contains adistribution of aerosol particle sizes. Although the average particlesize or MMAD, (Mass Median Aerodynamic Diameter) can be controlled, andthe spread of particle sizes can be reduced by varying the nebulizationconditions, the particles themselves are inevitably spread over a rangeof sizes.

Manifold 8 is preferably heated at a temperature sufficient to causeevaporation from the droplets, the aerosol particles become somewhatsmaller as they transit through the manifold 8. Those particles thatexit the manifold through the first chamber inlet ports 15 and 16,closest the manifold inlet, have a MMAD which is not significantlysmaller than that which enters the manifold through manifold inlets 13and 14. However, the particles that exit the manifold at the chamberinlet ports 21 and 22 distal to the manifold inlet have spent a longertime in the manifold 8 and there has been evaporation and a consequentreduction in particle size. As a result, the MMAD of these particles isreduced relative to its initial size. This will apply regardless of theinitial size of the particles.

Thus, as the chamber inlet ports are moved further away from themanifold inlet, the droplet size issuing from that inlet port decreases.That is the aerosol particle size at outlet 21, 22<the aerosol particlesize at outlet 19, 20<the aerosol particle size at outlet 17, 18<theaerosol particle size at outlet 15, 16.

The temperature of the droplets as they exit the manifold increases as afunction of the amount of time spent in the manifold. For example, thedroplets entering chamber 2 through chamber inlets 21 and 22 are notonly smaller than the droplets exiting through chamber inlets 15 and 16,they are also at a higher temperature.

The resultant small droplets tend to move upwards, especially as aresult of the air flow towards passive outlet vents 27 and 28 at the topof the chamber. However, the device still operates viably if the passivevent is located elsewhere in the chamber, including at the bottom of thesterilization chamber 2.

Thus, in the present invention the velocity of the aerosol droplets inthe chamber is rather low. This is advantageous, since high velocitydroplets tend to splatter on the surface, leading in some cases to anuneven build up of sterilant. A large build up of droplets isproblematical as it means that either longer drying time is required todry the article, or that there is an increased risk of residual materialbeing left on the article. Residual sterilant, such as peroxide, can beinjurious to users or patients.

To further reduce the velocity of the droplets, the chamber inlet portsas shown in FIG. 4 are in the form of ducts 29 (or nozzles) having anoff centre orifice 30 which leads to the aerosol being directed awayfrom the object to be sterilised. In the present invention, the aerosolis directed to the side of the ultrasound probe. This is shown in FIG.5, which is a horizontal cross section through the chamber. The gas flow31 a and 31 b is to either side of the plane 32 defined by the manifold8. The nozzles 29 and outlets 30 cause the flow to be away from plane 32at an angle such that the probe 10 is contacted only at a shallow ortangential angle.

FIG. 6 shows the arrangement in a chamber 2 of substantially circularcross section. The chamber wall 2 causes the gas flows 33 a and 33 b tobegin to circulate in a smooth manner near the chamber wall. Thedroplets are thus aimed at the void space in the chamber 2 around thesides of probe 10, rather than being directed at the probe itself. Thedroplets thus enter the chamber 2 at velocity, but because of the longerpath available to the droplets they have the opportunity to slow andthen diffuse around the chamber (downwards for large droplets, upwardsfor small droplets) until they contacting the probe 10 at low velocity.Larger droplets will be more inclined to take a more linear path, withless inward vortexing. Accordingly, larger particles will take a paththat leads them into contact with chamber wall 2, which is heated andthus causes the larger droplets to evaporate.

FIGS. 5 and 6 have the chamber enlarged and simplified for clarity. Inactuality, the chamber 2 is preferably conformed as closely as possibleto the shape of the article. Whilst sufficient space needs to be presentin the chamber to allow the mist to lose velocity, the chamber isotherwise sized as small as practicable.

FIG. 7 shows a horizontal cross section of a manifold arrangement wherethe aerosol is introduced from one side only. The gas flow 31 b isdirected to one side of the plane 32 defined by the manifold 8. Thenozzles 29 and outlets 30 cause the flow to be away from plane 32 at anangle such that the probe 10 is contacted only at a shallow ortangential angle.

FIG. 8 shows an arrangement similar to FIG. 6, but where the manifold isconfigured along one side of the chamber only. A single chamber inletport can be used as shown, configured in such a way that the flow istangential to the surface of an object (usually an object of a knownpredetermined shape) in the chamber. A single chamber inlet port issufficient to create a vortexing flow. The chamber wall 2 still directsgas flow 33 b to begin circulating in a smooth manner near the chamberwall. The droplets are thus aimed at the void space in the chamber 2around the sides of probe 10, rather than being directed at the probeitself. The droplets thus enter the chamber 2 at velocity, but becauseof the longer path available to the droplets they have the opportunityto slow and then diffuse around the chamber (downwards for largedroplets, upwards for small droplets) until they contact the probe 10 atlow velocity.

The tangential flow can also be achieved by having the manifold ormanifolds offset from the central axis of the chamber. FIG. 9 shows howa manifold 8 may be positioned offset from the axis 32. In such a case,it is not necessary to have duct 29 direct flow away from the article.It can be seen that this configuration maintains flow 33 b tangential tothe article, while still providing vortex separation.

FIG. 10 shows a similar configuration to FIG. 8, but illustrates in asimplified form the different paths taken by varying sized droplets.Smaller droplets follow the gas flow around the chamber, as shown bypath 34. Larger droplets have a higher linear momentum than smallerdroplets as they exit from manifold 8. The largest droplets will havethe most linear path 35, which leads them to collide with chamber wall 2at point 36. Because the chamber is heated, the larger dropletsevaporate. Thus, the vortexing is a means of separating and selectivelyremoving larger droplets from the chamber. A more even, dense mist ofsmaller droplets is thus available for sterilization.

1-34. (canceled)
 35. Sterilization apparatus including: a sterilizationchamber; detent means to maintain an article to be sterilized at apredetermined position in the chamber; and a manifold for introducing asterilant aerosol to the sterilization chamber for the disinfection ofan article, the manifold defining the terminal portion of a fluidpathway from an aerosol generator to the sterilization chamber, saidmanifold comprising at least one chamber inlet port for introducingaerosol into the sterilizing chamber and being configured to providedirectional aerosol flow tangential to at least part of the surface ofthe article, wherein the manifold is configured to provide directionalaerosol flow such that the article does not receive a direct flow ofaerosol from the manifold.
 36. Sterilization apparatus according toclaim 46, further including a passive vent.
 37. Sterilization apparatusaccording to claim 46, wherein there is at least one aerosol exit pointpositioned above the central vertical position of the chamber. 38.Sterilization apparatus according to claim 46, wherein the detent meanscomprises a collar to sealingly engage a portion of the article in thechamber and to restrain the article from contact with the chamber walls.39. Sterilization apparatus according to claim 46, wherein a chamberwall is heated.
 40. Sterilization apparatus according to claim 46,wherein the manifold and chamber in combination are configured toprovide a vortexing aerosol flow.
 41. Sterilization apparatus accordingto claim 51, wherein the article to be sterilized is at a point centralto the vortexing aerosol flow.